When is the gender of a shiny patch Pokemon determined?

Question

Is the gender of the Pokemon determined when you enter the patch or when the patch first appears on screen?

Comments

I haven't done Poke radar in a while, but from what I remember from using cute charm, it seemed that gender was determined when the patch was generated, since I got the lower gender ratio with my Cute Charm Lopunny at the front of my party versus when I switched it to the front after the patch generated.

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Are there any practical benefits to knowing the answer to this?

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I originally asked because I was hunting togepi which has a higher chance to be male and I was going for a female so I needed to know if I needed to have my Cute Charm Pokemon in the front of my party before generating the shiny patch or if I could switch my Cute Charm Pokemon to the front right before I entered the patch.

As stated above I believe gender is determined when the patch is generated but I never went back to confirm and answer the question :/

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Gotcha. It's kind of irrelevant when you can just faint your Cute Charm Pokemon and keep it at the front of your party constantly, right?

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...
I never once considered that previously.
I feel like an idiot.
But at the same time my cute charm Mon had to be level 50 or something and I don't think I had it leveled up at the time, so I think the thought process was get the shiny patch, swap the cute charm Pokemon in real quick, hope the chain doesn't break, and do the encounter, but that never would have worked anyways.